Table::as_ref, a reference of vector is force cast to slice. There are multiple problems here:
- To guarantee the size is correct, we have to first do
Vec::shrink_to_fit. The function requires a mutable reference, so we have to force cast from immutable to mutable, which is UB.
- Even if (1) is sound,
&[T] still might not have the same layout. Treating them equally may lead to UB.